Using an image as overlay/reference to a new photo create a short video from one image to the other, or simply compare the two images . Personally I created the application to take photos of a place and compare these photos with identical images of the same place many years ago.
First you select overlay image from you camera roll. Then take a new photo and use the chosen overlay image to compare and fit the new image that you want to shot. Now you have two identical images - the overlay and the new one - and can create a small video from the overlay to the new image.